Physicsbody Doesn't Adhere to Node's Anchor Point

physicsBody is misaligned with spriteNode

The anchorPoint determines where the node's texture is drawn relative to the node's position. It simply does not affect physics bodies because it's a purely visual property (a texture offset).

For physics-driven nodes it is actually counter-productive to change the anchorPoint from its default because that will change the point around which the texture will rotate. And the physics body will usually also change the node's rotation.

So even if you were to move the physics body shape's vertices to match the sprite with a modified anchorPoint, the physics shape will be misaligned with the image as soon as the body starts rotating. And it'll seem to behave weird.

Plus whatever you want to achieve using anchorPoint you can more flexibly achieve by using the node hierarchy to your advantage. Use a SKNode as the physics node, and add a non-physics sprite node as child to that node and offset it the way you wanted the image to be offset by changing the sprite's anchorPoint.

You end up having two nodes, one invisible representing the physics body and one (or more) sprite(s) representing the visuals for the body but not necessarily tied to the body's center position.

swift physicsbody is not matching up to image size

An alternate to working with physics is to use the recently added to iOS 10 SKTilemapNode to create the background. Each tile can be tagged with data to indicate if the tile is ground or not. You then focus on how the player moves relative to the tiles. There are currently not a lot of examples to show this working, the WWDC 2016: What's new in SpriteKit shows this briefly. Other resources include a top down example which shows at least how to build the background tilemap and some background info on why physics engines don't provide the best experience for platformers. Kenney's is a good source of tiles for platformer artwork.

Related Topics